The above compilers are "free" but not "public-domain."
Apart from ObjectAda by Aonix, they are distributed under FSF "copyleft."
"Copyleft" software (e.g. GNU compilers) means there is no warranty, and you
have permission to copy, modify, and further distribute the source. But
you can't charge anyone for the code, even if modified. Finally, distributed
code (always including source) must be subject to exactly the same conditions.
These compilers are free to the extent that you don't pay money to buy them;
you only pay with your own time to copy and install them.